OTHER GLACIERS OF PRINCE WILLIAM SOUND 379 Passage outside Icy Bay. We feel that Glenn's map, corroborated by Seton Karr's sketch, strongly suggests a maintenance of the 1794 position for over a century. By 1908, as Grant states specificallyl and as his map shows, there had been a great retreat; but he does not discuss the question whether it was a gradual retreat from 1794 to 1908, or a rapid one during the last few years of this period. He says "a traverse of the shoreline of this bay in 1908 shows it to be about 11 miles in length with a tidewater glacier at its head. On the north side of the bay, 6 miles from its head, is a smaller bay, nearly two miles in length; and at the head of this bay are two tide-water glaciers. The description of Whidbey, who was attached to Vancouver's exploratory expedition of 1794, states that this bay was four and a half miles deep and was terminated by a perpendicular cliff of ice. This would seem to indicate a retreat of ice in the axis of Icy Bay of some six and a half miles from 1794 to 1908." Relationships of Forest Growth. Our study of the vegetation in Icy Bay is interesting in connection with the description by Whidbey in 1794 and the position of the glacier as indicated on his map. Northeast of Nassau Fiord the forest is everywhere thick and mature, containing trees from 24 to 32 inches in diameter. The annual rings in a number of them were counted in 1910 and three trees about 24 inches in diameter were found to be 113, 120 and 122 years old. There were trees of about the same diameters, and about as thickly set, all along tne coast up to and including the small island northeast of the entrance to Nassau Fiord. These are not stunted trees, even those nearest the glaciers being well-developed. As Whidbey's visit was 116 years before ours of 1910, the presence of trees 120 to 122 years old proves clearly that the glacier could not have extended quite as far to the northeast in 1794 as the site of these trees. Along a sharply defined line near the entrance of Nassau Fiord, however, this mature forest ends, and the interior shores of Nassau Fiord, the mountain between Princeton and Chenega Glaciers, and the shores of Icy Bay from that point southwestward, have only scattered trees, none of which seem to be more than a score of years old. On the first prominent rock point inside of Nassau Fiord (near Photo. Sta. D, Fig. 56) the higher part of the barren zone has scattered willows, alders, and young spruces and hemlocks at an elevation of about 200 feet above sea level, the oldest one counted having 22 annual rings, though some of the others may have been even older. Nearer sea level the slopes are absolutely barren. This suggests that the ice front observed by Whidbey was maintained up to rather recent times, as we interpret Glenn's map to show also. On and near the col between Icy Bay and Port Bainbridge there are scattered conifers which from a distance seem to be of good size. We did not ascertain whether these extend down to sea level or not, nor how old they are. If it should prove that there are mature trees at sea level in this part of Icy Bay, it would suggest either (a) a forest advancing over the low col from Port Bainbridge, before the Tiger Glacier portion of the dismembered Icy Bay Glacier had retreated to its present position, or (b) that the expanded ice tongue of 1787-1794 was supplied wholly by the Chenega and Princeton Glaciers which emerged from Nassau Fiord and filled this part of Icy Bay without being joined by Tiger Glacier, the upper part of the inlet being either an arm of the sea or a lake. This latter interpretation, made in 1910, is at variance with the statement of Grant,3 * Grant, TJ. S., Jouin. Geol., Vol. XVII, 1909, pp. 670-671. "Op. tit., p. 671.